Does staying up late make you fat?

Lack of sleep makes you crabby.

But can staying up late make you fat? Or diabetic? Or increase heart disease risk?

Can forcing your body to ignore its evolutionarily-programmed day-night/sleep-wakefulness cycle also distort health, even when sleep is adequate?

Yet another study adds to the growing clinical literature documenting the lack of sleep, or, in this case, the "violation" of circadian rhythms that occurs with unpredictable or shifting sleep patterns.

In this small study of 10 men and women, forcing them to sleep on an unnatural 28-hour per "day" schedule, causing a dyssynchrony with natural day-night cycles, yielded increased glucose (blood sugar) levels, poor response to insulin, increased blood pressure. It also led to a decrease in leptin levels, a phenomenon that can trigger increased appetite.

Such circadian misalignment was meant to recreate the distorted day-night cycles of shift workers, a group that is unusually prone to diabetes and heart disease. This study further confirms that there are indeed unhealthy physiologic consequences of defying normal day-night sleep cycles.

This study suggests that, not only is sufficient sleep important for health, but the predictability and concordance with normal circadian cycles is also important.

Add to this previous studies demonstrating an association with sleep deprivation and low HDL/high triglycerides (Kaneita Y, et al 2008) and increased likelihood of having a positive heart scan (coronary calcium) score (King CR et al 2008), and it is increasingly clear that sleep is a crucial factor for overall health. It may even be a helpful strategy to control weight.

A full report on the importance of sleep is planned for the Track Your Plaque website.

Comments (5) -

  • mike V

    3/3/2009 5:58:00 PM |

    I noticed that your Grassroots Health piece was *posted* shortly after 5 AM.
    Dr Davis, I know I am not alone in the hope that you are personally getting sufficient sleep!
    This hope is not entirely altruistic. We need you around here!

    Mike V

    (Incidentally, thanks for the Grassroots tip. I joined immediately when I spotted the list of star scientists supporting the group). From my point of view, it was well worth your "insomnia"!

  • Trinkwasser

    3/7/2009 2:38:00 PM |

    I wonder here about cause and effect, my "natural" daylength is around 26 hours anyway. There was a recent BBC Horizon programme about the body clock where one researcher claimed she saw higher BG responses after the evening meal and therefore people should eat their carbs at breakfast.

    Now in common with most Type 2s and many Type 1s my carb intolerance is far worse in the morning (I suspect diurnal variation in insulin resistance) so I'm wondering where she found these subjects. Are "normals" that different in their glucose response? I do best with low carb high protein moderate fat breakfasts and can do twice the carbs in the evening while maintaining normoglycemia, many people have a far steeper slope. I'm wondering if the lipids somehow slow the (pituitary) body clock. Certainly I sleep better and wake up better on low carbs.

  • mike V

    3/8/2009 4:53:00 AM |


    Googling "diurnal insulin resistance/sensitivity" will produce plenty of studies about this topic.

    This British one suggests that individual diurnal variability is much greater in diabetics than in non-diabetics.

    I imagine that you must already be well aware of other factors that could affect BG response such as gastric emptying rate, glycemic index of food and food combinations, food acidity etc.

    Mike V
    Note: I am neither diabetic nor a doctor. I do happen to have an interest in your topic, insulin mimetics such as cinnamon, sleep, the effects of melatonin, and possible connections with the other "western" diseases.

  • Trinkwasser

    3/12/2009 11:12:00 PM |

    Interesting stuff with some references I will chase up later, thanks.

    I also have a suspicion that IR at the muscle receptors and the liver/ alpha cells may also be decoupled. My lipids and BG readings tell me I have my IR under control but while I don't do Dawn Phenomenon as such I can still get diurnal variations in whether my liver will dump too much glucose when I don't need it (morning) or refuse to dump when I do (afternoon).

    I've learned to tweak my BG manually against exertion levels and alpha lipoic acid has also helped even things out. Long term a Primal type diet and learning to run on ketones rather than glucose as a primary fuel has helped no end. Siestas seem to give me a second peak in IR, I hadn't really connected sleep cycles to the dyslipidemia before.

    Dammit, when are they going to release Endocrine System SP1? We've been waiting millenia for this.

  • buy jeans

    11/3/2010 10:38:08 PM |

    Yet another study adds to the growing clinical literature documenting the lack of sleep, or, in this case, the "violation" of circadian rhythms that occurs with unpredictable or shifting sleep patterns.